Issue 59

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P. Munafò et alii, Frattura ed Integrità Strutturale, 59 (2022) 89-104; DOI: 10.3221/IGF-ESIS.59.07

Adhesive

EPX 1

EPX 2

EPX 3

EPXRN

Chemical base Consistency

Two-part epoxy Controlled flow

Two-part epoxy Thixotropic Paste

Wt (min) At (°C) St (°C) τ (MPa) σ t (MPa) Et (MPa) ε t **(%)

90 ÷ 300 15 ÷ 25 -50 ÷ 120

15 ÷ 45

15 ÷ 25

> 5

< 80

10 ÷ 35

33.50*

(24.9 ÷ 30.7) *

(29 ÷ 36) *

6 6

- - -

3000

1800

5000

Use

Structural

Semi-structural

* On aluminium-steel adherents **At failure

Table 3: Technical and mechanical parameters of the adhesives reported by the manufacturers.

E XPERIMENTS

Single-lap shear tests hear tests are carried out to evaluate the effectiveness of the adhesive joint between GFRP adherends and to verify the mechanical contribution of the nylon reinforcement applied in the middle plane of the adhesive layer. For each configuration three specimens were assembled and tested. The geometry of the specimens was manufactured according to ISO 4587 [24]. The adherends had a width of 25 mm and a length of 100 mm; the overlap length was 12.7 mm. The thickness of the adherends was 5 mm. The thickness of the adhesive layer varies from 2 to 4 mm for unreinforced and reinforced joints, respectively. The geometry of the specimens is depicted in Figs. 2-3. The nylon fabric was first manually cleaned in order to remove any impurities (e.g. dust particles), dried and brought to environmental conditions at the time of the bonding phase. The surfaces of the GFRP adherends were treated in the bonding region by manual abrasion with sandblasting paper and degreased with acetone and isopropyl alcohol. S

GFRP Adherend

12,7 mm

25 mm

100 mm

GFRP Adherend

Epoxy resin

GFRP Adherend

2 mm

12 mm

100 mm

5 mm

Figure 2: Unreinforced Single-lap specimens’ geometry (mm), section view and plan view.

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